


Of Heat vision and Heartbeats

by Locks_and_keys



Category: Supergirl (TV 2015)
Genre: Domestic Fluff, Established Relationship, F/F, Fluff, SuperCorp, heatvision, what even is cannon
Language: English
Status: Completed
Published: 2020-06-08
Updated: 2020-12-03
Packaged: 2021-03-03 21:47:14
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,527
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24602593
Author URL: https://archiveofourown.org/users/Locks_and_keys/pseuds/Locks_and_keys
Summary: A couple of instances where Lena Luthor sees Kara's heat vision up close. Life with an alien girlfriend is full of surprises.
Relationships: Clark Kent/Lois Lane, Kara Danvers/Lena Luthor
Comments: 22
Kudos: 509





	1. Chapter 1

**Author's Note:**

> Ok so basically I'm slightly obsessed with the idea of Kara's heat vision. I've always loved the way they animated it in the show, and I had a few head cannons about it ever since I saw her cook a god damned turkey with it in that one episode. Enjoy : )

She won’t ask.

She can’t.

This lunch is going too well.

It’ll just have to wait, curiosity be damned. 

“Can you see when you use your heat vision?” Lena blurts out suddenly, failing to resist. She wants to smack herself. Kara blinks at her, chewing her mouthful of bagel slowly and giving her a puzzled look.

“Wh-what?” she finally says after a few seconds of silence, a bit taken aback at the sudden question. She turns in her seat to face the young CEO more directly. “It’s just that,” Lena continues, prompted to further explanation at the lack of response, “knowing what I know of the biology of human eyes and light optics, wouldn’t the outward light generated by your heat vision interfere with the light reflecting back into your pupils from your surroundings? Don’t you just see a white light?” 

“Have...have you been wondering that for a while?” She asks with an amused laugh. Lena just stares expectantly. “Mmmm, well,” Kara starts, setting down the rest of her bagel and fidgeting with a loose thread on the sleeve of her pastel pink cardigan, “I’m not really sure how it all works to be honest with you, but my vision does get a little…” she trails off, waving her hands around as she searches for the right word, “bright? I guess?” 

Lena does her best to suppress a smile at the endearingly goofy explanation. 

“You know,” She starts in a teasing voice with a raised eyebrow, “for a journalist with a Pulitzer that wasn’t a very good explanation.” Kara laughs lightly at her own expense and shakes her head. 

“Would you... umm,” She hesitates, her smile dropping a bit as she looks around the room briefly and cocks her head slightly to the side, a tell that Lena has learned to recognise as Kara using her super hearing to make sure no one else is within earshot, “would you like to see it real quick?” 

Lena raises her eyebrows in surprise. 

“Well, I know it can take a lot out of you, and Isn’t it a bit dangerous to be shooting off lasers in my office?” She asks, setting her black coffee down on the table in front of them next to Kara’s outrageously sweet frappuccino concoction. 

“Maybe, but I know you’re curious, and I promise to be careful” Kara challenges with a wink, biting back an excited grin. Lena bites her lip in indecision, torn between satisfying her curiosity and saving herself from explaining a pair of scorch marks on her office wall to Jess later. She nods, deciding to trust Kara. Kara seems to wiggle a bit in excitement at the affirmation, reaching up to take off her glasses and folding them carefully in her lap. It’s nice that they can finally share things like this. Lena imagines that it must feel freeing on Kara’s end. 

“Ok, here we go.” She mutters to herself. There’s a slight humming noise and Kara closes her eyes. Lena gasps when Kara opens them a second later, her eyes now glowing blue with solar energy. Lena can feel the heat of it hit her from where she’s sitting like a campfire, and she can’t deny that it’s more than a bit intimidating. 

“Woah.” She whispers in awe. Kara isn’t quite looking at her, instead she’s turned and is facing more towards the center of the room, which is probably for Lena’s benefit, since looking directly at her eyes leaves bright spots in her vision like welding without a mask. The glow seems to illuminate the rest of her features, highlighting her jawline and dusting her cheekbones with a red kind of light as the heat shines through from under her skin. The unmistakable power seems to make her sit up straighter. Lena’s mouth falls open slightly, drinking her in. It’s as if her insides were made of stars. “Your eyes…” She trails off, sounding a bit dumbstruck, “they’re like...supernovas…”

Kara laughs a bit self consciously, blinking a few times as the glow fades and the humming dissipates, her eyes returning to normal. 

“What did you think?” She asks quietly. Lena stares at her for a few seconds before leaning forward and kissing her softly. Kara’s eyes flutter closed as she returns it. 

“I think you looked beautiful.” She whispers against her lips when they break apart. Kara leans in and touches their foreheads together, humming as she threads her fingers through Lena’s hair. 

“I’ve never really thought of it as something beautiful.” She whispers, nudging Lena’s nose with hers and kissing her softly again. “But if it gets me kissed like _that_ ,” She says with a grin against Lena’s lips, “then who am I to argue?” 

***

Lena gets to see Kara’s heat vision again later that week, but it’s under less than ideal circumstances. Unlike her minimally styled office, with windows giving a view to the tops of the skyscrapers of National City’s finest up and coming corporations on a clear blue day, the middle of city square (Where Supergirl is currently fighting an alien hostile) is full of distractions, panicked civilians, and one very worried former DEO director slash big sister. 

Lena had seen the livestream coverage just a few moments before Alex had called her cell, and before Alex could tell her not to she’s riding the elevator down to the lobby and headed directly towards the faint sounds of explosions. Rushing down two blocks, dodging panicked people, and slipping past the DEO agents making a perimeter and guiding people to the side streets away from the fight. 

The alien stands over Kara, menacing and strong as it’s eyes look her over. It’s got four arms from what Lena can see, and they’re all as thick as tree trunks. Kara raises an arm to hit it, but the alien catches her fist with a giant green hand, twisting it painfully as Kara falls on one knee in exhaustion. The beast laughs at the sight before it hits her hard across the face with the back of it’s other hand. The sound of the slap hits the air and Lena lets out a shocked gasp, which wasn’t the best idea, since the alien’s head swivels right to her, who stands alone and singled out past all the DEO blockades. Lena should probably think about running right about now, but before she can convince her legs to move the blinding light of Kara’s heat vision shoots the alien square in the chest, knocking it back several feet. 

As if it were some kind of que, the DEO agents pull up and surround the pair with armored trucks, agents pouring out like swarming ants to subdue the creature as it stumbles under the onslaught of Kara’s continuous heat vision. Before long it’s backed up into the open hatch style doors of one of the trucks, kicking and howling against the restraints slapped on it as the solar rays hitting it stop. Lena watches as Kara stands up, wobbles, then falls backward onto the concrete. It crunches loudly where her back hits it, fracturing like an eggshell and looking hilariously similar to some kind of cartoon gag. Well, it _will_ be hilarious, later, after she finds out if Kara’s ok. 

Lena rushes forward, sinking to her knees to take Kara's face in her hands and prop her up in her lap. The effects of kryptonian heat vision are still leaving her face, and Lena’s hands sting a bit on her warm skin like they’re wrapped around a mug of coffee that’s too hot to drink. Her irises still flare, two impossibly bright lights shining through pale blue sea glass, the delicate veins of her sockets shadowboxed and glowing underneath orange and red lit skin, residual heat hitting Lena’s face as it comes off in waves. Kara doesn’t seem to be able to see her clearly, a familiar crinkle appearing between her eyes. ‘ _I guess that answers my question from the other day’,_ she thinks to herself dryly. The joke fails to shake off her nerves, because if she’s being honest, It’s almost scary. Kara staring back at her with eyes unseeing, with the power to burn her alive. Almost like staring down the chamber of a loaded gun. 

“Kara, it’s ok, it’s me.” She reassures. The vulnerability isn’t lost on Lena, but she refuses to look away as Kara's breathing slows and her eyes find her’s, finally returning to their cool blue color as they flash with recognition. The low buzzing that accompanies Kara’s heat vision fizzles out, and soon all is quiet. 

“Lena!” Kara gasps, reaching forward with shaking hands and resting them on her shoulders like a zombie rising up from the grave in a melodramatic black and white film. Lena gives her a crooked smile, a sigh of relief escaping her lips and moving the blonde wisps of Kara’s hair around gently like a breeze. 

“Hello darling.” She says, pulling her into a hug. Kara relaxes against her, wrapping her arms around her waist and holding tight, tired muscles rippling under the slippery blue material of the supersuit. 

“Did you solarflare?” 

“No, I don’t think so, but did I win?” She sighs against the shell of Lena’s ear, the hint of a smile in her tone. The CEO scoffs and buries her nose into the super’s neck, breathing in the scent of ozone and smoke coming off her cape. She’s clearly fine, the idiot. 

“Yes Kara,” She states dryly, “you won.” She leans back to press a kiss to Kara’s cheek, before continuing with a playful quirk of her eyebrow, “If you can call destroying my favorite city block ‘winning’, that is. I mean just look at the memorial fountain, or, look at where it used to be, since you’ve reduced it to rubble when you plowed right through it.” 

“It was kind of ugly anyway…” 

***

It’s a slow day in National City. People walk past on the street outside Kara’s new loft, wearing less layers in the warmer weather that’s been hitting them recently as they head towards the park or the shopping district, duck into cafes, ride their bikes, hail bright yellow taxis or laugh with their friends, no doubt enjoying their days off. Lena has the day off too for once, (which hasn’t happened in ages), and the sky as far as she can see out the windows is free of clouds, but it might as well be a storming mess in Lena’s opinion. Or a hurricane. Or at the very least a grey overcast to match her anxiety level. 

Normally Lena would be enjoying herself, if she and Kara were simply having take out lunch from Noonans together in her new loft, paid for by her girlfriend’s new reporter job, or eating something she cooked. But it isn’t like any other day, and Lena’s running through all the possible escape routes to get her out of the social hellscape she’s about to enter as she checks the oven timer and then the clock on the wall for the millionth time. She can’t take it anymore. 

“Ok but what if they don’t like me?” Lena says suddenly, turning towards the kryptonian, who’s been sitting on one of the bar stools on the opposite side of the island countertop watching her girlfriend wreak havoc on her new kitchen for the last hour. Kara turns and looks at her in surprise, a reject sticky bun from Lena’s first attempt at them this morning skewered on a fork paused halfway to her mouth. Surprise turns into concern as her eyebrows knit together and a reassuring smile tugs at the corner of her mouth. 

“Lena, they’ve met you already. Plus, what’s not to like?” She asks innocently, reaching up to adjust the glasses that Lena now knows she doesn’t need. Lena just rolls her eyes and fiddles with the ends of her apron strings as Kara flashes her a megawatt smile that rivals the sunshine streaming through the window. She’s about to remind the blonde of the last time she met Clarke Kent, and how he had been less than thrilled to share a room with her, how now that they’re dating _and_ she knows about their _secret identities_ he’s bound to be even more distrusting of her. No doubt a bit overprotective too, especially with this whole, ‘ _come check out my new loft with Lois and have lunch with me and my girlfriend_ ’ scenario that Kara had scheduled. She’s about to voice these insecurities, but she’s interrupted by the oven timer going off loudly next to her. 

“Are you sure they like-” Lena starts to ask before cutting herself off with a horrified gasp, hands white knuckling the oven door handle as she stands rigid staring at the dish inside. Kara cringes at the sudden silence, sliding carefully off the seat and quickly rounding the island to stand by her side to investigate. 

“Lena?” She asks cautiously, slowly putting a hand on her girlfriend’s shoulder. Lena doesn’t react, staring intently through the column of steam coming out of the oven looking like she’s seen a ghost. 

“ _I_ _t’s undercooked!_ ” she squeaks in a strained whisper, eyes bulging in dread. Beside her Kara immediately relaxes, exhaling loudly in relief. 

“Oh, thank Rao! I thought you were having an aneurysm or something.” She says with a laugh. Lena turns to face her slowly, and Kara works overtime to wipe the smile off her own face and school her expression when she sees the crazed look in Lena’s green eyes. 

“They’re going to be here any minute Kara! THIS IS A DISASTER!” She shrieks as she covers her face with her hands. 

“Hey, hey, it’s ok!” Kara reassures hurriedly, gently nudging Lena’s hip and pushing her to the side so she can reach into the oven and retrieve the dish with her bare hands. Lena just shuffles to the side, peeking through her fingers in defeat. “I have a little trick for this. Eliza made me do it all the time when I was a kid. It really came in handy one time when our stove broke in the middle of Hanukkah and I had to heat the cooking oil for everything.” 

“Wait, do what?” Lena questions, lowering her hands enough to give Kara a suspicious look before gasping in realization as the blonde puts the baking dish on the counter and takes a resolute step back, removing her glasses. “You mean use your heat vision? Does that even work?!” 

“Well, we had Latkes and Sufganiyot that year!” Kara says cheerfully, shooting her a quick smile before screwing up her face in concentration. There’s a familiar tension in the air, accompanied by a high pitched buzzing, before familiar blue beams shoot from Kara’s eyes. She holds for five seconds, counting them silently out on the fingers of her right hand, (an endearingly childlike habit, Lena would say), before she blinks rapidly, eyes returning to normal as the dish steams ominously on the counter. With a nervous wimper Lena padds forward to inspect it, before breaking into a grin and whipping around, raven hair flying over her shoulder.

“Kara Danvers, you are my hero.” She beams, stepping to Kara’s side and standing on her tiptoes to press a kiss to her cheek. Kara giggles and turns her head to get a proper kiss, resting her hands on Lena’s hips and pulling her closer. There’s a knock at the door and they break apart, Lena’s smile immediately dropping. Kara lowers her glasses a bit to peer at the direction of the knock and Kara gasps, face splitting into a grin. 

“What? What do you see?” Lena asks. “It’s so unfair that you can see through walls.” 

“Lena!” She whispers excitedly, now buzzing with energy and tapping rapidly on Lena’s arm, “ _They brought baby Jon!_ ” Before Lena can even process that statement a burst of superspeed brings Kara right to the door, and Lena has just enough time to rip off her ‘kiss the CEO’ apron and smooth down her hair before she flings open. Lena sees that it’s true. Lois Lane brushes past the doorway and wraps Kara in a hug, leaving Clarke in the doorway. He stands there, all stern posture with a tight smile, but Lena finds the intimidation factor of an official introduction greatly decreasing as she sees Jon’s small form kicking in a front facing baby carrier strapped to his chest, little sock covered feet sticking out. 

“Kara, Lena, I’m glad we could meet up this week.” Lois greets good naturedly, giving Lena a nod that she returns. She takes a few more steps into the room before realizing that Clarke isn’t following. Instead he stares straight at Lena, looking just as uncomfortable as Lena feels.

“Hello Lena…” He says with a forced smile that he’s clearly trying his best to make look genuine. Lena almost winces at the awkwardness but returns with a smile of her own that probably looks just as strained. Lois seems to remember he’s there, grabbing him by his sleeve and dragging him into the apartment and ending their staring match before throwing herself into the chair across from Kara melodramatically. Kara and her share a brief glance, and for a second Lena has hope that she’ll make it out of this alive. 


	2. Chapter 2

**Notes for the Chapter:**

> Here's a little continuation! Not much heat vision, but maybe I just fell a little in love with the idea of Lena having to babysit a half Kryptonian rascal.

“I’m sorry, what?!” Lena asks, sure she’s heard her girlfriend wrong.

“I know! I know!” Kara apologizes as she tugs on her boots frantically and looks around for her cape, flinging the throw pillows off the couch haphazardly before picking the whole thing up, gasping loudly in relief and snatching the corner of the red material out from underneath one of the legs. She sets the furniture down with a bang that shakes the floor and makes Lena jump.

“Kara! I can’t watch him by myself!” She yelps, following Kara to the open window and shaking her by the shoulders before she jumps out to fly off into danger. 

“Lena, you’ll be fine! You're great with kids!” She reassures, reaching behind her ear to turn on her comms, which she immediately regrets with a wince as Alex’s voice thunders at her from the earpiece. “I’m sorry but I really have to go.” 

“Yeah! But most of the children I deal with aren’t half Kryptonian!” Lena argues frantically, ignoring her reassurance as she reaches up to run her fingers through her curtain of dark hair. She stares hard at her superhero, wide eyed and panicked. A stricken look flashes over Kara’s features as her eyes dart from outside towards the danger far away to her CEO girlfriend who’s looking ready to pull her own hair out. 

“Lena, love, I’ll be right back. You won’t even notice I’m gone!” Kara exclaims, darting forward to press a kiss to Lena’s forehead. She doesn’t wait for her to respond, shooting out of the window with a crack, followed by a far away boom as she breaks the sound barrier high above National City’s surrounding outskirts in her haste to rush to superman’s aid. Off to kiss babies and shake hands. ‘Not like there’s a perfectly good baby here to kiss or anything’, Lena thinks spitefully. 

A horrible silence fills the house, punctuated only by the soft cooing coming from further inside. With timid steps, Lena creeps over to the baby carrier on the kitchen island, reaching forward with a slow hand as she pulls off the blanket on top of it to reveal a now very awake baby. He babbles sleepily, kicking his little socked feet out in the air as she stares her down with the house of El eyes. Steely and blue like Kara and Clarke’s. 

“Ok Lena,” she coaches, pumping herself up, “You’re one of the youngest CEO’s in the world. You rendered an alien virus inert. You’ve saved Supergirl many times. You are a capable, independent, classy, billionaire lady. You can do this.”

She looks down at the child, resolutely rolling her shoulders before scooping him up in her arms with a handful of soft blanket and cradles him. “Jon El- Kent, I believe we’re stuck with each other.” 

***

It’s going fine, really. The first half hour passes without any major incidents. The little guy falls back asleep quickly after Lena gives him some attention and lets him have the indestructible binky from the baby bag that Lois had brought over earlier in the day before catching her redeye flight to Star city for a big press conference. Lena was set to attend that conference too on behalf of LCorp, but her media manager and Jess had insisted she sit this one out. She had agreed begrudgingly, only after arguing with them for a good thirty minutes each, bringing up LCorp’s many recent advancements in biochemistry and plans for green energy as she did so. Jess had only dug her heels in deeper at that, assuring that the LCorp representative attending in her place was completely capable of bringing up those points herself, and, unlike Lena, wasn’t the target of a recent wave of assassination attempts. 

But yes, as Lena sits on the couch, (which sat slightly askew with the way that Kara had picked it up earlier in her frantic search for her cape) she returns work emails, outlines meeting minutes, and drafts an official statement about LCorp’s newest project, all while Jon snoozes peacefully in his baby chair on the floor by her feet. Even she has to agree that things are going fine. 

That is, until he wakes up a second time. 

Then things go haywire. Lena doesn’t really know what she expected to happen when he started crying, but it wasn’t that she would be nearly incapacitated by the lung capacity the kid has. 

He lets out an ungodly wail of a cry, like most babies do, but this one makes the dishes in the kitchen cabinets rattle dangerously across the room with the power behind a half Kryptonian’s voice. Lena’s only defense is to slam her palms over her ears to block the sound reactively with a wince. She’s suddenly very thankful that she’s using her home just in the outskirts of the city instead of her penthouse full of nosey rich neighbors that file noise complaints at the drop of a hat. A baby crying with the same volume of a jet taking off in her living room would definitely make waves. Crawling on the floor pathetically like someone trying to escape a fire she reaches the bag she got the binky from, which had been set next to her chair on the other side of the room, and starts searching for something to help. Jon continues to fuss loudly, nearly splitting Lena’s head in two. 

She digs past D.E.O developed milk bottles and teething toys as heavy as dumbbells until she finds a small package at the bottom of the bag with something that looks like high tech earplugs. A blue sticky note on it shows a heart and a line of X’s and O’s as well as the words “For Lena” that looks like it was drawn by Clark’s firm handwriting. Lena desperately rips them out of the packaging and puts them on. Activating with a touch, they instantly numb the sound of Jon’s cries as if she’s hearing him from underwater, and she’s never appreciated the man of steel more. She quickly gets up to give Jon some attention. He calms back down while later, but Lena doesn’t take out the earplugs for the next two hours.

“Don’t take it personal, Jon. It's just a precautionary measure, you know, in case you wanna try and shatter my eardrums again.” She jokes fondly, grinning as she pinches his cheek. 

***

“Lena! I’m back!” Kara calls into the house. She shakes the bits of concrete fragments out of her hair and pats the desert dust off her super suit as best she can before going through the backdoor of the second home, finally letting herself relax after the long fight. She was sent home from the aftermath a bit early, and she hopes Kal unsnares from the bureaucratic trap of DEO paperwork he’d been asked to go through soon so he can catch his flight to Star City for the last few days of the conference with Lois. 

“Kara! We’re in here!” Lena’s voice calls out from the kitchen. Lena sounds a bit off, voice coming out strained, and it shifts Kara back to hero mode immediately, worst case scenarios flashing in her mind at light speed. Without another word she bolts into the hallway, whipping around into the kitchen, only to see Lena look up at her, wide eyed.

“Be careful!” She shouts, pointing to the floor in front of Kara, but it’s too late, and Kara watches helplessly as her world flips. On the bright side, she has a great view of the ceiling now. Not that she has any idea why she’s on her back. Lena’s laughter rings out clearly, bouncing around the kitchen and flooding Kara’s chest with warmth as she sits up and looks around, a bit dazed at being slammed horizontally. With surprise, she looks at the floor to find it covered in a thick patch of...ice?

“Umm, Lena?” Kara asks, confusion evident in her voice as she rises, holding onto the countertop for stability on the ice. “Why does your kitchen look like that one episode of Tom and Jerry where Jerry turns the house into an ice rink?”

Lena gives her an exasperated but fond look, rounding the counter to kiss her cheek and gesturing over her shoulder towards the baby carrier on the floor where Jon gurgles mischievously. 

“ _Someone_ woke up from a nap and discovered how fun it is to ice over the floor with freezebreath.” She says dryly. Kara whips around to face him, beaming.

“Did someone discover a new power?!” She preens in a high pitched baby voice before turning back to Lena and dropping it. “That's fantastic! He’s barely a year old. Me and Clarke didn't get freeze breath till we were in our twenties!” She exclaims, bouncing on the balls of her feet. 

Lena smiles at her, enjoying her girlfriend’s glowing pride and joy for a few seconds before glancing back at the icy kitchen floor expectantly. Kara seems to get the hint, firing up her heat vision as Lena crosses over out of her way to grab Jon out of his carrier. 

The next fifteen minutes are spent with Lena holding back joyous laughter as she bounces a cackling Jon in her arms, the pair watching as Kara turns the kitchen into a steam room. Her eyes glow a jack o'lantern orange through the mist as it billows up around her, condensing on the cabinets and countertops before finally dissipating out the open windows. Lena’s hair is completely ruined by the humidity, but she supposes it’s better than having the set of Disney on ice in her kitchen. Kara powers down, eyes slowly turning from bright suns to their familiar ice blue with a quieting hum, and Lena hands a wiggling Jon over to her. 


End file.
